Eliminating racial/ethnic disparities in health and health care is a national priority, and obesity is a prime target. During the last 30 years in the U.S., the prevalence of obesity among children has dramatically increased, sparing no age group. By the preschool years, racial/ethnic disparities in obesity prevalence are already present, suggesting that disparities in childhood obesity prevalence have their origins in the earliest stages of life. Several risk factors during pregnancy, infancy, and early childhood have been found to be associated with the development of obesity. However, few studies have examined racial/ethnic differences in these prenatal and early childhood risk factors for childhood obesity. It is possible that racial/ethnic differences in early life risk factors for obesity might contribute to the high prevalence of obesity among minority preschool age children and beyond. In addition, psychosocial and societal stressors, prevalent in racial/ethnic minority populations, may lead to physiologic processes that increase obesity risk. Maternal stress, experiences of racism and interpersonal violence remain unexplored as contributors to childhood obesity and its risk factors. The overall goal of this study is to use both quantitative and qualitative methods to study racial/ethnic disparities in early life risk factors for childhood obesity. In the quantitative phase of this project, we will study African-American, Hispanic, and white children who are participants of two, ongoing, NIH-funded, cohort studies of pregnant women and their children in Massachusetts: Project Viva and Project ACCESS (Asthma Coalition on Community, Environment, and Social Stress). Together, these cohorts comprise over 2000 racially, ethnically, and socioeconomically diverse mother-infant pairs. In the qualitative phase of this study, we will enhance our quantitative findings by conducting focus group discussions with racial/ethnic minority women during pregnancy, infancy, and early childhood to further probe the underlying reasons for disparities in early life obesity-related risk factors. The members of the interdisciplinary research team are well qualified to conduct the study, as they have pioneered epidemiologic studies on the origins of obesity during pregnancy and the postpartum period, and have extensive experience in examining racial/ethnic disparities in health and health care. With its innovative design, foundation in evidence, and feasibility, the proposed study may very well open up new avenues for interventions to prevent childhood obesity in the very segments of the US population who need it most.